High-efficiency, multi-stage centrifugal pump and method of assembly

Abstract

A high-efficiency, multi-stage centrifugal pump and method of assembly. The pump can include three pump stages with each one of the three pump stages including a front casing, a back casing, an impeller, and a bladed diffuser. The front casing and the back casing are removeably coupled around the impeller and the bladed diffuser. In the three-stage pump, the fluid can be pumped at a flow rate between about 300 liters per second and about 500 liters per second with an efficiency between about 86% and about 91%. The method includes separately casting, machining, and polishing each one of the front casing, the back casing, the impeller, and the bladed diffuser.

1. A high-efficiency, multi-stage pump for pumping a fluid and being driven by a motor, the multi-stage pump comprising:
 three pump stages, each one of the three pump stages including a front casing, a back casing, an impeller, and a bladed diffuser, the impeller at least partially encircling the bladed diffuser; 
 the front casing and the back casing being removably coupled around the impeller and the bladed diffuser to allow access to polish substantially entire inner surfaces of the front casing and the back casing when the front casing and the back casing are uncoupled from each other; 
 the fluid being pumped through the three pump stages at a flow rate between about 300 liters per second and about 500 liters per second with an efficiency between about 86% and about 91% due at least in part to polishing substantially entire inner surfaces of the front casing and the back casing. 
 
     
     
       2. The multi-stage pump of  claim 1  and further comprising an inlet and an outlet, and wherein the motor is driving the multi-stage pump at the inlet. 
     
     
       3. The multi-stage pump of  claim 2  and further comprising a short-radius elbow attached to the inlet. 
     
     
       4. The multi-stage pump of  claim 1  wherein the impeller includes an impeller eye which receives the fluid and impeller blades that release the fluid substantially radially outward; and wherein the bladed diffuser includes diffuser blades that direct the fluid toward one of the three pump stages. 
     
     
       5. The multi-stage pump of  claim 4  wherein the impeller blades are angled between about 18 degrees and about 22.5 degrees. 
     
     
       6. The multi-stage pump of  claim 1  wherein the front casing, the back casing, the impeller, and the bladed diffuser are made of stainless steel. 
     
     
       7. The multi-stage pump of  claim 1  wherein the front casing, the back casing, the impeller, and the bladed diffuser are manufactured by a casting process. 
     
     
       8. A method for assembling a stage of a multi-stage pump, the method comprising:
 separately casting a front casing, a back casing, an impeller, and a bladed diffuser; 
 machining the front casing, back casing, the impeller, and the bladed diffuser; 
 polishing an entire first inner surface of the front casing, polishing an entire second inner surface of the back casing, polishing an entire surface of the impeller, and polishing the bladed diffuser, each of the entire first inner surface of the front casing, the entire second inner surface of the back casing, and the entire surface of the impeller defining an internal passage for fluid flow through the stage when the stage is assembled; and 
 removably coupling the front casing and the back casing together around the impeller and the bladed diffuser.